CSF, Fail2Ban, BFD and APF are software what rely on iptables and expand/automate their functions.
You have two choices when it comes to Centos: iptables and firewalld and both work on Ceontos 7.
Personally i use iptables because i used them before so no need to learn all new stuff for firewalld. But for someone like you who is new and need to learn regardless of the firewall i would say pick one and stick with your choice.
I recommend looking at FirewallD, it was actually really easy to set up and seems to make a lot more sense than iptables ever did (tho admittedly I never really looked into them as I used CSF).